In recent years, in mobile terminal devices (hereafter, also referred to as “mobile terminal” as an abbreviation), smart phones have been prevalent in place of the conventional mobile telephones having mechanical button keys (hereafter, also referred to as “old-type mobile phone”).
In the general old-type mobile phones, text entries have been made with the use of button keys with a mechanical structure. Further, since compact mobile terminals are desirable, the mobile terminal cannot be equipped with a full keyboard. Therefore, the old-type mobile phones have a “ten-key” with a mechanical structure, and the text entries to the old-type mobile phone have been made with the use of this ten-key. As the exemplary text entry system using the ten-key, so called “toggle entry” has been known. The toggle entry is an entry system in which one key is allocated with a plurality of characters such as the characters of one row of the Japanese syllabary or three or four characters of the alphabet, and every time a key is pressed down, next character appears sequentially as a candidate for entering text. For example, in the toggle entry, every time the key with “a” written thereon is pressed down, the candidate for entering text changes in the order of “a→i→u→e→o→a→ . . . ” and every time the key with “ABC” written thereon is pressed down, the candidate for entering text changes in the order of “A→B→C→A→ . . . ”.
Further, some of the ten-keys on the old-type mobile phones have the convex shapes, which are different from respective keys on its touch surfaces in order to allow a user to distinguish respective keys of the ten-key by the user's feeling in a finger without looking at the ten-key. This supports the text entry by the visually impaired users.
On the other hand, text entry to a smart phone is often made by the user touching by the user's finger to the touch panel that is laminated on the LCD (Liquid Crystal Display) provided on the surface of the smart phone. Further, the ten-key used in the text entry is displayed on the LCD as an image. The LCD displays not only the ten-key but also various images according to the usage of the smart phone. Further, the surface of the general touch panel can be a flat shape only. Therefore, it is difficult to form the convex shapes for distinguishing respective keys on the touch panel of the smart phone, unlike in the old-type mobile phone. Therefore, as a technique for supporting a visually impaired user to made the text entry to the smart phone, there is a technique of voice notification by reading aloud the touched key when any of the ten-key on the touch panel is touched. For example, in the toggle entry, a voice tells “ei” when the key with “ABC” written thereon is touched for one time, a voice tells “bi” when it is touched for two times, and a voice tells “si” when it is touched for three times. As such, the voice notification of the touched key allows the visually impaired user and the like to know the position of the desired key on the touch panel.
Related-art examples are described, for example, in Japanese Laid-open Patent Publication No. 2011-013730 and International Publication Pamphlet No. WO2003/027826.
However, when the user of the smart phone has visual impairment, it is difficult to know, by the visual observation, the desired key that the user intends to touch. Further, as mentioned above, the surface of the general touch panel can take a flat shape only. Therefore, when the user of the smart phone has visual impairment, when the user makes the text entry without looking at the key image, or the like, the key which is different from the desired key recognized by the user may be touched by the user. In particular, when the user intends to successively touch the same key for making the toggle entry, there is a case that every time the key is touched, the touched position shifts and the key different from the desired key is touched. For example, when the user who intends to enter “C” using the toggle entry touches the “ABC” key three times, there is a case that every time the key is touched, the touched position shifts, resulting in that, at a third touch, the user may touch “DEF” key neighboring on the right of the “ABC” key.